The studies are part of a long range project which is designed to yield considerable knowledge regarding the substrate structural requirements of estrogen and steroid sulfotransferases in endocrine (bovine adrenal) and non-endocrine (bovine liver) tissues. The information gained with these easily available enzymes will be used to facilitate the isolation and study of the estrogen and steroid sulfotransferases of the human breast tumor. It is anticipated that these studies will provide guidelines for the development of specific active site-directed irreversible inhibitors of these enzymes. Such inhibitors may be utilized in the future for studies designed to elucidate the importance of sulfation in steroid synthesis and metabolism in normal and tumor tissues. At the present time we have in our laboratory both of the sulfotransferase enzymes (estrogen and steroid alcohol). The bovine adrenal estrogen sulfotransferase is now highly purified and the steroid alcohol sulfotransferase has been purified 20X to date and we expect to have this enzyme homogeneous by the end of this grant year. Detailed examinations of the substrate specificity and inhibition characteristics have been carried out on the estrogen sulfating enzyme and soon will be completed on the steroid alcohol sulfotransferase. The development of specific, active site-directed, irreversible inhibitors of these enzymes via affinity labeling of the binding site may well lead directly to biologically useful antisteroids which will be of use in elucidating the importance of steroid alcohol and estrogen sulfotransferases in steroid hormone synthesis, metabolism and activity in normal and tumor tissues.